Process for producing cyanic combinations



Dec. '14 1926. a

- o. STALHANE PROCESS FOR rnonucms cmuc couamumns Filed llarch 31. 1926 Jrwerzfor": 1?

.45 heated by Patented Dec. 14, 1926.

UNITED STATES PATENT OFFICE.

OTTO STALHANE, .OF STOCKHOLM, SWEDEN.

PROCESS FOR PRODUCING CYANIC CQMBINATIONS.

Application filed March a1, 1926, Serial No. 98,793, and in Sweden n vnber 1a, 1924.

This invention relates 'to improvements in such processes for producing cyanic'combinations, wherein carbide or a mixture consisting of carbon, and combinations of the alkali metals or the alkaline earth metals, and possibly some catalyzer, is brought into contact withnitrogen at high temperatures.

It has been tried to produce cyanie combinations in such a way that raw material of the above mentioned kind was heated together with nitrogen in electric shaft furnaces, the charge itself serving as resistance to the heating current. As, however, the charge is a second class conductor, it has in practice proved impossible to give to the whole of the charge an evenly distributed temperature suitable for the chemical reactions. Therefore, the yield of cyanic combinations in such processes has been very low. It has also been tried to carry out the processby heating the charge together with nitrogen in retorts by means of combustion gases. On account of the low heat conductivity. of the charge, in the hitherto known processes of this kind using retorts with a, large cross-section the retorts must be heated to a'very high temperature, on account of the comparatively long way the heat must pass through the charge in the retort to reach its interior, and because the temperature of reaction is as high as about 1000 C. This entailed the disadvantage that the retort walls quickly. were destroyed and that the charge was very unevenly heated, the parts close to the retort walls being heated too high giving the charge a. tendency to melt, whereas in the interior. of the charge the temperature as a rule was too low, which resulted in a low yield.

- Accord'ng to this invention the described disadvantages are avoided by carrying out the process in pipes With a very small crosssection compared with the hitherto used retorts. The walls of the pipes are to be electric current conducted through'the walls of the pipes or through .special. heating elements surrounding the- .pipes. The pipes should be of such dimensions that the heat had to pass a distance from the heated walls to the interior of the charge of only 0,8" to.1,2" and at any rate" At the same time a temperature injurious to the pipe walls is avoided.

In order to lessen the heat consumption.

the nitrogen is led through the pipes in the opposite direction to the charge, so that-the end. product leaves the pipes at a comparatively'low temperature, while the gas mixture leaving the pipes is cooled down leaving heatto thenewly introduced charge material.

By way of example an arrangementto carry out the process with electric heating is shown'in the accompanying drawing.

Fig. 1 shows a vertical section upon the line 1I in Fig. 20f the furnace arrangement. Fig. 2 shows a vertical section upon the line I1-Ilin Fig. 1.

12 denotes the furnace Walls within which a number of pipes 13 of metal or fireproof charge to be treated is fed into the pipes in the form of briquettes or lumps through the feeding pipe 22. In alignment with the pipes 6 a plunger 23 is arranged that by means of an excentric disc 25 or the-like arranged upon the shaft 24 is given a reciprocating motion.- --During this motion the plunger pushes fdrward briquettes 29 from pipe 22 into the pipe 6. The briquettes are thus gradually fed through the pipe 6 by the plunger to finally fall down into the water container 20. The pipes 6 are in their middle part provided with electric heating elements 26 by means of which the pipes and the charge in them can be heated to the temperature suitable for the process.

The necessary nitrogen is introdueed, partly through the pipe 27, partly through the pipe 28. The gas from the pipe 28 passes around and along the pipes 6 and is intended to protect the heating elements 26 from oxidation. mixed with the nitrogen coming from the pipe 27 enters the pipes 6 and leaves through the feed opening 22 as indicated by The nitrogen from the pipe 28 isarrows. The soluble cyanic combinations formed at the high temperature in the pipes 6 are dissolved in the water in the container 20 and the insoluble substances are brought away by the-transport screw 21.

In the case the pipes 6 are made of metal the pipes may be heated by conducting an electric current through the walls of the pipes.

The section of the pipes may preferably be circular, but may also be elliptic or rectangular or of other shape.

The pipes may be arranged vertically, horizontally or inclined.

The pipes may also be heated by hot combustion gases or other hot gases sweeping around them.

To bring about a more intimate contact 7 between the nitrogen and the different parts of the charge the briquettes may be perforated. They may for instance be provided with a central channel in the feed di rection, or they may .be provided with several channels in the feed direction, or at the circumference be provided with grooves.

' The pipes 6 may also be composed of two concentric pipes, the charge and the nitrogen being fed through the space between the pipes. The briquettes should then have a form that corresponds to the cross-section of the said space.

Pulverized charging material may also be used and may then be formed into briquettes or one or more strings and forced into the pipes by some suitable feeding device.

I claim:

The continual process for producing cyanic compounds by reaction under heating between nitrogen and briquettes containing carbon and alkah metal compound 1n which the charge is continually fed in countercurrent to the nitrogen gas through electrically heated pipes arranged in a furnace and of such dimensions that the Way of the heat from the heated pipe walls to the interior of the charge is comparatively short and not exceeding 3".

In witness whereof I have hereunto set my hand.

OTTO STALHANE. 

